Cahill was saying that the court speed in 2016 was about the same as 2017 in Australia. However the balls were changed in 2017 and these ones didn't fluff up quite as easily as the ones they used before. That was the change that helped the fast court players like Mischa Zverev do well here. It has been often said that fast courts disadvantage Nadal. To me that is simply not true. The low bouncing courts disadvantage Nadal but fast courts with high enough bounce work great for him. Faster courts reduce margin of error. So while someone like Roger can benefit from a quick court when he is playing well, when he is off his game, a quick court can hurt him as well. It is quite telling that AO17 was quicker than Wimbledon 16 and the difference in bounce is almost nothing. It is okay in my mind for Grass to not be super quick but really not okay for grass to have hard court like bounce.